Abstract: A control device for a discharge lamp, comprising an electronic switch connected between an AC supply source and a loading circuit including the discharge lamp to be controlled, and a control circuit delivering pulses to a control electrode of the switch so as to control the state of conduction thereof; the control circuit comprises means for detecting the passages through zero of the voltage at the terminals of the loading circuit and generating means responsive to the detecting means for generating pulses controlling the passage of the switch to the non-conductive state, whereby non-conduction periods of the switch are controlled for an adjustable duration in response to the passages through zero of the voltage at the terminals of the loading circuit.